Apparatus for air floatation separation



Dec. 7, 1937.

E. M. RUSK APPARATUS FOR AIR FLOA'IATION SEPARATION 2 Sheets-Sheet l Filed Sept. 8, 1933 BY Q/ ATTORNEY6 Dec. 7, 1937. E. M. RUSK APPARATUS FOR AIR FLOATATION SEPARATION Filed Sept. 8, 1933 2 Sheets-Sheet 2 INVENTOR n ifiLZQuSk ATTORIIJEYS Patented Dec; 7, 1937 IUNITED'STATES PATENT". OFFICE Edwin M. Rusk, Seattle, Wash.

Application September 8, 1933, Serial No. 688,860

1 Claim. ,(01. 209-466) My invention relates to the art of separating l or classifying materials and more particularly to apparatus for air floatation separation.

Many machines have been created for thepurpose of separating and classifying materials and many different methods have been used in creating those machines each adapted to a specific purpose. In my present machine I employ the floatation properties of air underpressureto provide the separating, stratifying or classifying of materials. While there may be many industrial uses for my equipment I prefer to describe my equipment as it would be constructed and used in the recovery of metals from sand or from finely crushed materials.

When used as a gold recovery machine, for example, a very finely divided air-stream is directed under a column of gold bearing sand, and the pressure is so regulated that the grains of sand are lifted or held in the state of suspension similar in character to quick sand except that there is no water or other liquid present.

The principal object of my present invention is to provide a separating device for dry particles 25 of difierent specific gravity wherein that separation is accomplished by causing the lighter particles to rise to the surface and flow over one edge of the hopper while the heavier particles are collected in the bottom of the re- 30 ceptacle.

A further object of my invention is to provide a device which will cause the stratification of dry particles so that they may be separated one from another.

A further object of my present invention is to provide a separating device which will separate dry particles of different specific gravity as a substantially continuous operation. Other and more specific objects will be appar- 40 out from the following description taken in connection with the accompanying drawings, wherein a Figure 1 is a perspective view showing a separating unit built after the teachings of my invention.

Figure 2 is an exploded perspective view of the hopper bottom or air distributing means.

Figure 3 is a longitudinal vertical section thru my machine. a

Figure4 is a cross sectional view along the line 4-4ofFigure3.

Referring to the drawings, throughout which like reference characters indicate like parts, nu-

merals l0 and I2 designate a plurality of hopper- 55 like receptacles of which any suitalk number may be employed. These hoppers are provided with the rather high sides I4 and i6 and end walls of different height as probably best shown in Figure 3 in which the end from which the machine is fed as I8 is considerably higher than the discharge end 20. The bottom of each receptacle is provided with an air-distributing means. In this connection it is desired to point out that means must be provided which will insure a very finely divided air stream. One solution that has 10 been found quite satisfactory is to use material such as billiard cloth and to form it as a cup as indicated at 22. This can best be put in place by having its downwardly extending edges as 24 encircle an air distributing cone 26. Then .the 15 whole unit can be snugly fitted inside the bottom of each compartment or receptacle as It or l2 and secured there by any suitable means as by the latch member 28.

Now, to provide that the cloth cup 22 will not be bowed upwardly when the air draft is applied to it I find it desirable to super-impose upon the upper side of cup 22 a grill like retaining member the column of sand under the influence of the air blast should be the same entirely across the bot- .tom of each receptacle to the end that equal resistance will be encountered and there will be no tendency for the finely divided air streams to unite and act as a jet'on any portion of the sand.

Suitable means must be provided for drawing off the heavier materials at the bottom of each receptacle or compartment. This can be accomplished by venting the lower portion of the re ceptacle or after the showing of my present illuso tration, by providing a slide cut-'ofi as 32 adapted to slide within the housing member 34 so .that when the slide is forced clear in, the sand may pass entirely over it without coming in contact with cloth 22 and recoveries of the desired heavy materials can then be effected by removing the air cone 26.

Each compartment as l0, l2 etc. needs to be provided with a source of air under pressure. In my present illustration I have indicated a pressure blower 36. This I prefer to be of the so called impeller type which has the capacity of creating pressures up to 10 or 12 pounds per square inch, and at the same time being a high speed unit can handle large volumes of air. Any

suitable motive power might be supplied to blower 36 altho in keeping with the general desire to use a machine of this type for gold recovery in those localities where water is at a premium, I have indicated an air cooled internal combustion motor as 38. The blower is provided with an intake as 40 which, in certain instances, might need be screened, and a discharge pipe 42. This discharge by suitable Siamese connections can be led to any desired number of receptacles or bins. In the illustrations I have shown only two bins. I wish it to be clearly understood that conditions govern the choice of the number of bins employed and there might be any reasonable number of the.

same or in case of batch separation possibly only one might be used. Under certain conditions where the recovery of metals might be very difficult as, for instance, very flne'and flaky materials it might be desirable to have several receptacles or bins disposed one below the other. Then again if a continuous operation is desirable it may be necessary to have one more bin than is essential for the required separation in that one bin can be shut off, as by slide 32, the metal recoveries made, and while that operation is taking place thematerials .can be permitted to flow into the next lower bin.

Normally I prefer that a hopper, as 44, be provided to insure a fairly even'fiow of materials thru my machine and further usually find it sufficient to provide a simple control gate as 45. Under certain conditions it might be necessary to provide a mechanical feeding arrangement to insure the proper feeding of wet materials or materials which tend to pack. In some instances it may be necessary to provide screening arrangements of which there are many different types and as they form no part of my invention I have not shown the same. It is necessary however that the material passing thru the machi'ne be of more or less uniform composition inasmuch as the air pressure is quite critical and any factor which would change the rate of air passage thru the materials would necessitate manual control of the air pressure. This control I have provided by placing a butterfly valve as 48 in each of the I air ducts 50.

Under certain conditions it is found desirable to provide a vibrating means for my equipment. In the present instance I have shown this as an eccentric weight 52 which is secured to the extension of the blower shaft as 54. This in turn is suitably journaled on bearings 56 which are secured to the main frame of the machine 58. To the end of making my machine as portable as possible, I have provided the blower and its motor as a unit on a secondary frame 60 which is adapted to be secured to the main frame 58 as by brackets 62. This permits the two units to be separated for transportation and ease of handling.

Method of operation are supported from each other by a film of air.

In this condition, metal which may be present with the sand has no supporting means and as the air pressure is only sufficient to float in part the sand, the heavier metals sink to the bottom of the bin. Even the finest gold particles resting on a floating grain of sand are suflicient to revolve that grain of sand and cause the metal to drop.

When the sand is aerated" or floating as it were, it acts much as water and the illustration in Figure 3 is quite a truthful reproduction, in that the sand will flow from one level to the next just as so much water would do but as the sand moves from wall 18 to wall 20 it is being constantly agitated by the air stream and if desired is sifted by the agitating means. The truth of the statement that the air actually supports or floats the sand is evident when the air blast is turned off as when this occurs the sand actually settles down to about two thirds of its original height proving quite conclusively that the air properly adjusted will actually hold the sand in suspension. A most interesting experiment can be conducted by laying a coin on the sand when it is at rest and naturally the coin stays right on the surface due to the packing of the sand particles upon one another. As soon as the air is turned on however, the coin will not stayon the surface of the sand for an instant but disappears below the surface and falls to the bottom of the binjust as tho it were placed in a vessel of water.

In stratifying different materials of substantially the same specific gravity a most peculiar phenomenon is experienced. For instance different kinds of sand whose specific gravity is very nearly the same, but which differs to a degree, when placed in this machine will quickly assume a stratification corresponding to their specific gravity-the heavier materials in the bottom and the lighter materials at the top. The same-is true of grain. Take two grains as wheat and barley for instance. The wheat will settle quickly tothe bottom whereas the barley being a lighter material will seek the upper level. It is believed, it will be clear that once the materials are stratifle'd their separation can be easily accomplished it being necessary only to vent the bins at different elevations to provide this separation.

The foregoing description and the accompanying drawings are believed to clearly disclose a preferred embodiment of my invention but it will be understood that this disclosure is merely illustrative and that such changes in the invention may be made as are fairly within the scope and spirit of the following claim.

I claim:

In a stepped, multi-chamber, pneumatic, dry ore separator having an elevated feed hopper,

and including a separating chamber open at top and bottom and having a discharge wall with its bottom of said chamber, a separable retaining grid forming a weight and resting on said cover,

one wall of said chamber havinga slot above said grid for the insertion of a slide plate which is adapted to form an auxiliary chamber-bottom. EDWIN M. RUSK. 

